TY - JOUR
T1 - The impact of black wattle encroachment of indigenous grasslands on soil carbon, Eastern Cape, South Africa
AU - Oelofse, Myles
AU - Birch-Thomsen, Torben
AU - Magid, Jakob
AU - de Neergaard, Andreas
AU - van Deventer, Ross
AU - Bruun, Sander
AU - Hill, Trevor
PY - 2016/2/1
Y1 - 2016/2/1
N2 - Black wattle (Acacia mearnsii, De Wild.) is a fast growing tree species introduced into South Africa in the nineteenth century for commercial purposes. While being an important source of timber and firewood for local communities, black wattle is an aggressive invasive species and has pervasive adverse environmental impacts in South Africa. Little is known about the effects of black wattle encroachment on soil carbon, therefore the aim of this study was to investigate the impact of black wattle encroachment of natural grassland on soil carbon stocks and dynamics. Focussing on two sites in the Eastern Cape, South Africa, the study analysed carbon stocks in soil and litter on a chronosequence of black wattle stands of varying ages (up to >50 years) and compared these with adjacent native grassland. The study found that woody encroachment of grassland at one site had an insignificant effect on soil and litter carbon stocks. The second site showed a clear decline in combined soil and litter carbon stocks following wattle encroachment. The lowest stock was in the oldest wattle stand, meaning that carbon stocks are still declining after 50 years of encroachment. The results from the two sites demonstrate the importance of considering changes in soil carbon when evaluating ecosystem effects of invasive species.
AB - Black wattle (Acacia mearnsii, De Wild.) is a fast growing tree species introduced into South Africa in the nineteenth century for commercial purposes. While being an important source of timber and firewood for local communities, black wattle is an aggressive invasive species and has pervasive adverse environmental impacts in South Africa. Little is known about the effects of black wattle encroachment on soil carbon, therefore the aim of this study was to investigate the impact of black wattle encroachment of natural grassland on soil carbon stocks and dynamics. Focussing on two sites in the Eastern Cape, South Africa, the study analysed carbon stocks in soil and litter on a chronosequence of black wattle stands of varying ages (up to >50 years) and compared these with adjacent native grassland. The study found that woody encroachment of grassland at one site had an insignificant effect on soil and litter carbon stocks. The second site showed a clear decline in combined soil and litter carbon stocks following wattle encroachment. The lowest stock was in the oldest wattle stand, meaning that carbon stocks are still declining after 50 years of encroachment. The results from the two sites demonstrate the importance of considering changes in soil carbon when evaluating ecosystem effects of invasive species.
KW - Faculty of Science
KW - Acacia mearnsii
KW - Carbon Sequestration
KW - Invasive alien plants
KW - Soil organic matter
KW - Biomass
U2 - 10.1007/s10530-015-1017-x
DO - 10.1007/s10530-015-1017-x
M3 - Journal article
SN - 1387-3547
VL - 18
SP - 445
EP - 456
JO - Biological Invasions
JF - Biological Invasions
IS - 2
ER -